House siding, particularly that to give a clapboard appearance, has become extremely common in today's building materials. This siding falls into two general categories: plastic and metallic; the metallic being in most instances an aluminum composition. The panels in each instance have one of several designs to interlock and have alternate depths to accommodate insulation or a lesser depth referred to as "hollow backing".
The material is manufactured with the use of dies by either rolling or extruding and includes variour colors and textures. As in all mass produced materials, substantial inventories are maintained at the various marketing levels.
Particularly, the corner pieces require a different die to give a differnet depth to the panels, for that with insulation and that of hollow backing. On a continuous production, different machines will run the two types of corner pieces. Similarly, the inventories will also comprise stocking both "sizes". Again the different colors further compounds the production and stocking problems.